2008 Jeep Liberty 3.7 Sport - P0300

[jeepsRcool71]

HELP!! I recently purchased a 2008 Jeep Liberty from a Chevy dealership, it has spent more time back at the dealership than in my driveway. It had 39,500 miles on it when I purchased it on 4/30/2011. I've experienced intermittent issues with it running rough while driving and idling. Eventually the CEL comes on, and logs a P0300 code.. Multiple Random misfire code. When the issue happens it acts like its not getting enough gas and bogs down really bad, so I press harder on the gas, then the CEL comes on and then it will start to shake. The dealership doesn't know what direction to go in with it, and I'm at the end of my rope. The Chevy Dealership sent it to a Jeep Dealership, and they said since it has a P0300 code which is a generic historical code and it doesn't specifically point to anything so they can't do anything. :x

The O2 sensor, and spark plugs, have been changed but no luck.

 

[superj]

check your coil packs (that has multiple, right?)

 

[jeepsRcool71]

Thanks for the reply- Would that just give the random misfire code, or would it give a more specific code? The dealership is telling me that if it were a true misfire related to cylinders that it would give a more specific code pointing to which cylinder is affected. ie. P0301,02 etc..

 

[superj]

i don;t remember. its been a fair amount of time since my liberty.

is your exhaust clogged up?

 

[SteelHeadz]

That could be a mechanical or electrical failure. The best thing to do is monitor the PCM with the scantool and capture the event when it occurs. Thats what the dealer should have done.

 

[jeepsRcool71]

Why would the dealership say they sprayed carb cleaner in the carburator when the jeep doesn't have a carburator??? :???:

 

[SteelHeadz]

They are talking about adaptive numerators on the PCM. It's the air/fuel ratio that's stored in the PCM on the long term memory that is constantly monitored by the short term to achieve the stoichiometric ratio which is ultimately 14.6:1 ratio. Spraying a combustible aerosol into the throttle body will ultimately adjust the fuel trim on the pcm adaptive numerator but will not stay there long as soon as it relearns that the injectors are delivering a determined amount by the pcm. IMO, spraying the carb. cleaner is just a band aid.

 

[jeepsRcool71]

I was thinking that it was a bandaid, so since it first returned a value of 15 then they got it down to 5, what could that mean? Sorry, this area is getting really muddy, and I'm feeling really frustrated with their BS. Do you know what the fix or direction to go with this is ? I just spoke to a different Jeep dealership, and they're willing to take a look at the jeep, and seems to be familiar with this sort of Jeep issue. They mentioned that Jeeps are knowns for Carbon buildup on the valves, and didn't understand why the other dealerships are playing this game. I would like to report them to someone or somewhere, but just don't even know where to start.